Testosterone and cortisol are more predictive of choice behavior than a social nudge in adult males on a simple gift give-get task.

Reproducibility of social research is ambitious, and evidence supporting this argument is increasing in psychology and social science research. This may be attributed to, in part, the high volume of qualitative research methodology used in social research along with difficulties in the reliability of measurement techniques. Therefore, use of more and better objective measures to complement existing techniques in social research are necessitated. To highlight this point we explored the success of give-get nudge in adults. Nudge being a subtle intervention to influence choice, without restricting choice. We also wanted to explore whether testosterone and cortisol, as objective psychophysiological markers, could explain nudge outcome. Participants were asked what they would like to get for Christmas, or what they would like to give. They were then presented with two chocolates, one big and one small, and instructed to take as a "reward" for their participation with the knowledge there was one other participant to take chocolate after them. It was hypothesized that those asked to give something for Christmas would take the smaller reward and vice versa. Salivary testosterone and cortisol were measured prior to, and 10 min after completing the exercise. The nature of the nudge itself did not predict behavior, but the hormone measures did. We speculate that testosterone may focus an individual on the nature of the question (nudge), while cortisol encourages self-focus. These results support the need to combine existing social research techniques with more objective markers.